The following are co-pending applications in the same field showing the state of the art which are herein incorporated by reference:
1. Method and Apparatus for Automatically Handling, Assembly or Working on Objects, or "Targets", SN 348,803. PA1 2. Robot Calibration, SN 453,910 PA1 3. Electro-Optical Systems for Control of Robots, Manipulator Arms and Coordinate Measuring Machines, or "Robots and Manipulator Arms", SN 592,443. PA1 4. Robot Tractors SN 323,395, now U.S. Pat. No. 4,482,960. PA1 5. Robot Tractors, Vehicles and Machinery, SN 651,325.
These applications and the present invention are all commonly owned.
Flexible robot assembly is often very difficult in the absence of machine vision sensors to guide the operation. Even with such sensors, operation must be both accurate, ultra reliable, and fast enough to be justifiable relative to human labor. These criteria are seldom met by present day vision systems employing arbitrary gray level images and the like.
The target based invention described in reference 1 above has wide application to the assembly process. Described therein are several embodiments illustrating target based techniques which can overcome the limitations of present systems. The key to the use of the disclosed systems is that the target points on the part are easily discernable and unambiguous, after processing using rapid devices and other high speed analysis software.
The target system functions well because it is based on high contrast images and mathematical equations. To use targets one must know the part feature data base relative to the target points on the part. Targets on tooling, pallets and fixed members may also be of use. Special retro reflective targets give best contrast, but targets can be holes, corners or other easily determined natural part features.
Finally, where special targets are used which would not normally be present, techniques are disclosed to make these unobstrusive.